What do you mean by ”usually” here?
I’m certain all the regular name brands, eg JBL Bose Sonos B&O etc enable the device itself to be configured with a user set name via their app. I’m certain because I’ve used them and done so.
People buy the speaker, charge it and turn it on, pair, play music, throw the packaging away, that's it. Usually the bluetooth name refer to the brand and model which is much more convenient to know which one you are connecting to than giving it a silly name.
I wouldn't expect most people to know they can do it in the first place and even those who do like me don't bother most of the time.
As for other brands I own: Jlab, jawbone, pyle, and anker don't seem to have any such functionality that I can see.
So it's far from ubiquitous, sufficiently so that it makes no sense to presume that a bluetooth name is a message from a passenger and can be understood to have any intended meaning.
I don't see why people are hung up on this. Imagine even just 2 or 3 of the same model "JBL SpeakerName" nearby, how would you know whos is whos? Renaming is common.